Medical science has developed a wide variety of methods for counteracting the effects of cardiovascular disease including open heart and by-pass surgery. Non-surgical procedures such as percutaneous transluminal coronary angioplasty, laser angioplasty, and atherectomy have been developed.
One alternative to the aforementioned procedures is known as Transmyocardial Revascularization (TMR). In such procedures, channels are formed in the ventricle wall of the heart with a laser. These channels provide blood flow to ischemic heart muscle. A history and description of this method has been documented by Dr. M. Mirhoseini and M. Cayton on "Lasers in Cardiothoracic Surgery" in Lasers in General Surgery (Williams & Wilkins; 1989) pp. 216-233.
As described therein, a CO2 laser was used to produce channels in the ventricle from the epicardium through the myocardium. This procedure followed a surgical incision in the chest wall to expose the heart. Laser energy was transmitted from the laser to the epicardium by means of an articulated arm device of the type commonly used for CO2 laser surgery. The beam was coherent and traveled as a collimated beam of laser energy through the epicardium, the myocardium and the endocardium into the left ventricle cavity. The epicardium received the highest energy density and therefore normally had the largest area of heart tissue removed compared with the endocardium which was approximately 1-cm deep to the epicardium. The resultant channel through the myocardium was funnel-like. A problem associated with the above procedure arose because laser perforation of the epicardium caused bleeding from it outwardly from the left ventricle after the procedure. External pressure by the surgeon's hand on the epicardium of the heart was often needed to stop bleeding from the ventricle to the outside through the hole produced by the laser in the epicardium. However, this procedure was usually only partially successful because it resulted in a significant amount of blood loss and/or an excessive amount of time required to stop the bleeding. Both factors could jeopardize the success of the revascularization procedure.
In a proposed improvement in an TMR procedure described in Hardy U.S. Pat. No. 4,658,817, a needle was added to the distal tip of an articulated arm system, with a beam of laser energy being passed through the lumen of the needle. The metal tip of the needle of the device was used to pierce most of the myocardium and the laser beam then was used to create the desired channel through the remaining portion of the myocardium and through the adjacent endocardium. In the Hardy procedure, the hollow needle used to deliver laser light was subject to being clogged by tissue or blood which could flow into the needle, thus blocking the laser light from impinging the myocardium. Also, the metal rim of the needle could be damaged by the intense laser light and leave contaminating metal remains within the myocardium which are potentially hazardous.
Another proposed TMR procedure is described in the Aita, et al. U.S. Pat. No. 5,380,316. Aita, commenting on the Hardy needle device, contends that mechanical piercing was undesirable because it entailed some degree of tearing of the pierced tissue, and that tearing often leads to fibrosis as the mechanical tear heals, a factor that severely diminishes the effectiveness of the TMR treatment. Aita, et al. also contends that exposure to metal may cause fibrosis where the needle passes through tissue. The Aita, et al. patent describes an elongated flexible lasing apparatus which is guided to an area exterior to the patient's heart and irradiates the exterior surface to form a channel through the epicardium, myocardium and endocardium. Thus, in the Aita et al. procedure, the epicardium is irradiated at a high energy density and therefore should have a large area of heart tissue removed. Consequently, the Aita et al. procedure has the same problems and disadvantages as the prior Mirhoseini TMR procedure with respect to the aforementioned bleeding problem in the outer surface of the epicardium.
In U.S. Pat. No. 5,713,894, an improved apparatus and method for TMR procedures is disclosed. In this teaching, the epicardium membrane of the heart muscle is first penetrated mechanically by a hollow piecing member and thereafter the distal end of a laser transmitting fiber is moved forwardly through the myocardium as it emits pulses of laser energy to form a channel. When the fiber element is retracted and the piercing member is removed the opening that was made mechanically in the epicardium tends to close to prevent excessive bleeding from the channel formed in the myocardium. Other examples of myocardial revascularization devices with manual optical fiber advancement mechanisms include U.S. patent application Ser. No. 08/790,193 now allowed entitled "Improved Laser Device For TMR Procedures," and U.S. patent application Ser. No. 08/675,698, now allowed, entitled "Contiguous, Branched Transmyocardial Revascularization (TMR) Channel, Method & Device."
Other surgical techniques for performing TMR include U.S. patent applications Ser. No. 08/794,733 and Ser. No. 09/031,752. These disclosures teach of a viewing surgical scope apparatus that can introduce a visualization scope and a tissue ablation optical fiber for minimally invasive surgical use. These two disclosures also include a hand-held TMR optical fiber advancement and control handle assembly that attaches to an articulating handle member which in turn deflects the device's articulating distal tip assembly where the optical fiber egresses to perform the procedure. The U.S. patent application Ser. No. 08/794,733 also includes an auto-piercing mechanism in this handle assembly.
Under certain operating conditions, the characteristics of the epicardium membrane may vary so the physician may elect to use one or more different tip members on the hand-held device for carrying out the aforesaid improved TMR procedure. Also, it is desirable that the physician be able to pierce the epicardium in the most efficient manner using an auto-piercing mechanism thereby minimizing the size of the opening necessary to accommodate an advancing fiber element. The TMR device of the present invention solves these problems.
Additionally, many presently used hand-held TMR devices require manual finger control to advance the energy delivery devices such as an optical fiber while a physician fires the laser to create TMR channels. Thus, there is need for an automated TMR device.